Thank you, Jange and SS, for hitting the nail on the head. The Constitution of 1990 wasn't scrapped because of any specific flaws. Lest we forget, there was no debate at the time on the matter whatsoever. No, it was scrapped because an unreformed [and unreformable] terrorist movement demanded its unilateral abolition as the price of peace.
Nepal's supposedly democratic parties gave way and, in the name of restoring democracy, proceeded to run roughshod over the very principle of liberal constitutional democracy itself. Now, Nepalis are faced with the stark reality that their leaders have nothing credible or coherent to offer in place of the old constitution.
Whether a further extension is granted to the current train-wreck CA or a "fresh mandate" is sought for a new legislative body, Nepal's party leaders are not going to experience a sudden epiphany of constitutional inspiration. The complete ideological bankruptcy of the "Naya Nepal" experiment has been put on public display, and people are taking notice.